FIGS. 10(a) and (b) show a general configuration example of a pressure connection terminal. A conductor crimping portion 11 and a cover crimping portion 12 are provided at a rear portion of a terminal 10 in a position situated at a front and a position situated at a rear of the rear portion, respectively. The conductor crimping portion 11 has a U-shaped cross section and has a bottom plate 11A which is a common substrate of the terminal 10 which extends over an overall length thereof and a pair of left and right crimping pieces 11L, 11R which rise from side edges of the bottom plate 11A which face each other in a transverse direction. Likewise, the cover crimping portion 12 has a U-shaped cross section and has a bottom plate 12A and a pair of left and right crimping pieces 12L, 12R which rise from side edges of the bottom plate 12A which face each other in the transverse direction.
When connecting this terminal 10 to an electric wire W, firstly, a conductor Wa which is exposed by removing an insulation cover Wb at an end portion of the electric wire W is placed on the bottom plate 11A of the conductor crimping portion 11, and a portion of the electric wire W which is adjacent to the exposed conductor Wa and is still covered by the insulation cover Wb is placed on the bottom plate 12A of the cover crimping portion 12. Next, in this state, as FIG. 10(c) shows, a crimper (that is, an upper die) 101A and an anvil (that is, a lower die) 102A of a terminal crimping apparatus are driven to press the pair of left and right crimping pieces 11L, 11R of the conductor crimping portion 11 so that the crimping pieces are crimped while being rounded inwards by two arch-shaped crimping portions 111L, 111R each made up of an arc-like surface which are provided at a portion of the crimper 101A which faces the anvil 102A, whereby the conductor crimping portion 11 is pressure connected or crimped to the conductor Wa of the electric wire W. At the same time, the pair of left and right crimping pieces 12L, 12R of the cover crimping portion 12 are bent inwards, whereby the portion of the electric wire W which is covered by the insulation cover Wb is fixedly crimped. By crimping the conductor crimping portion 11 and the cover crimping portion 12 in the way described above, the terminal 10 and the electric wire are connected together.
When the terminal 10 and the electric wire W are connected together by means of crimping, it is known that the electrical connection performance and the mechanical connection performance vary depending particularly on the crimping quality between the conductor Wa and the conductor crimping portion 11. Then, a terminal crimping apparatus is proposed which includes a function to determine whether the crimping quality is good or bad by detecting an abnormality during a crimping operation of a terminal (for example, refer to Patent Literature 1).
As FIG. 11 shows, this terminal crimping apparatus 100 has a set of an anvil (that is, a lower die) 102A and a crimper (that is, an upper die) 101A which crimps a conductor crimping portion 11 for pressure connection and a set of an anvil 102B and a crimper 101B which crimps the cover crimping portion 12. By lowering the crimpers 101A, 101B, the terminal 10 and the electric wire W which are inserted between the anvils 102A, 102B and the crimpers 101A, 101B are pressure connected or crimped together. In addition, a pressure sensor 120 is installed in a base portion 110 which supports the anvils 102A, 102B, so that whether or not a proper crimping operation is performed is determined based on waveform data which shows a change with time of loads applied to the anvils 102A, 102B which are detected by the pressure sensor 120.
For example, as FIG. 12 shows, a crimping process is divided into several stages T1 to T3. Then, whether or not a proper crimping is performed is determined by verifying whether or not the characteristic waveforms of loads measured fall within a permissible range S which is set based on a reference waveform A resulting when a normal crimping operation is performed in the individual stages T1 to T3.